Pharmaceutical compounds

ABSTRACT

Benzimidazole derivatives of formula (I): (Formula (I)) wherein: R 1  is —(CH 2 ) m —R 7 , (Formula (II)) or (Formula (III)); R 2  is H, halo, —(CH 2 ) m —NH 2 , —(CH 2 ) n —C(═NH)—NH 2  or —(CH 2 ) n —NH—(CH 2 ) m —NHR 9 ; R 3  is H, F or Cl; each of R 4 , R 5  and R 6  is independently H or F; R 7  is C 1 -C 6  alkyl, CF 3 , —SO 2 R 11 , —NH—(CH 2 ) 2 —(NH) r —R 8 , —NH—CH(R 8 R 9 ) or a group of the following formula (A): (Formula (A)): W is —(CH 2 ) m —, —CH 2 —O—CH 2 —, —CH 2 —S—CH 2 —, —(CH 2 ) r —S(O) 2 —CH 2 — or —(CH 2 ) r —NR 8 —CH 2 —; m is an integer of 1 to 3; n is 1 or 2; p is 1 and V is CH; or p is 0 and V is N; q is 0 or 1; r is 0 or 1; R 8  is H, —SO 2 R 11 , —SO 2 CF 3 , —COR 11 , —C(O)OR 11 , —CON(R 9 ) 2  or —(CH 2 ) n SO 2 R 11 ; R 9  is H or C 1 -C 6  alkyl, each R 9  being the same or different when two are present; R 10  is —SO 2 R 11 , —SO 2 CF 3 , —COR 11 , —CON(R 9 ) 2  or —(CH 2 ) n SO 2 R 11 ; and R 11  is C 1 -C 6  alkyl; and the pharmaceutically acceptable salts thereof are inhibitors of RSV and can therefore be used to treat or prevent an RSV infection.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application represents the national stage entry of PCT International Application No. PCT/GB2018/053756 filed on Dec. 21, 2018, which claims the benefit of Great Britain Patent Application No. 1721812.4 filed on Dec. 22, 2017, the entire contents of which are incorporated herein by reference for all purposes.

FIELD OF THE INVENTION

The present invention relates to benzimidazole compounds and to their use in treating or preventing a respiratory syncytial virus (RSV) infection.

BACKGROUND TO THE INVENTION

RSV is a negative-sense, single-stranded RNA virus of the Paramyxoviridae family. RSV is readily transmitted by secretions from an infected person via surfaces or hand-to-hand transfer. Unlike influenza, it is not transmitted by small-particle aerosols. Following successful inoculation, the incubation period is between four and six days during which time the virus spreads from the nasopharynx to the lower respiratory tract by fusion of infected with uninfected cells and by sloughing of the necrotic epithelium. In infants, coupled with increased mucus secretion and oedema, this can lead to mucus plugging causing hyper-inflation and collapse of distal lung tissue indicative of bronchiolitis. Hypoxia is common and the ability to feed is often impaired because of respiratory distress. In RSV pneumonia, inflammatory infiltration of the airways consists of mononuclear cells and is more generalised, with involvement of the bronchioles, bronchi and alveoli. The duration and degree of viral shedding has been found to correlate with the clinical signs and severity of disease.

RSV is the leading cause of serious respiratory tract infections in infants and young children throughout the world. The highest morbidity and mortality occurs in those born prematurely and for those with chronic lung or heart disease, although many infants hospitalised for RSV infection are otherwise healthy. Severe RSV infection in infancy can lead to several years of recurrent wheezing and is linked to the later development of asthma.

RSV is also a major cause of morbidity and mortality in the elderly and in immunocompromised children and adults as well as those with chronic obstructive pulmonary disease (COPD) and congestive heart failure (CHF).

RSV has a seasonal incidence; it is highly predictable and occurs in the winters of both hemispheres, from September to May in Europe and North America, peaking in December and January, and can occur throughout the year in tropical countries. It affects >90% of infants and young children by the age of two years and as natural immunity is short-lived; many will be re-infected each year. As with influenza, in elderly people, RSV causes around 10% of winter hospitalisations with an associated mortality of 10%.

Current anti-RSV treatment involves the use of a monoclonal antibody to RSV, called palivizumab. Such use of palivizumab is a prophylactic, rather than therapeutic, treatment of RSV. Although this antibody is often effective, its use is restricted to preterm infants and infants at high risk. Indeed, its limited utility means that it is unavailable for many people in need of anti-RSV treatment. There is therefore an urgent need for effective alternatives to existing anti-RSV treatment.

Additionally, several compounds have been proposed as inhibitors of RSV, including benzimidazole-based compounds. For example, K D Combrink et al., Bioorganic & Medicinal Chemistry Letters, 17 (2007), 4784-4790 discloses the compound BMS-433771 and variants thereof. Further benzimidazole-based compounds are disclosed in WO-02/062290, WO-03/053344 and WO-10/103306.

WO 2013/068769 and WO2016/055780 disclose benzimidazole compounds having activity against RSV. However there exists a need to identify further compounds, and in particular compounds having favourable pharmacokinetic profiles.

SUMMARY OF THE INVENTION

It has now been found that a novel series of benzimidazole compounds are active as RSV inhibitors with favourable pharmacokinetics. Accordingly, the present invention provides a compound which is a benzimidazole of formula (I):

wherein:

R¹ is —(CH₂)_(m)—R⁷,

R² is H, halo, —(CH₂)_(m)—NH₂, —(CH₂)_(n)—C(═NH)—NH₂ or —(CH₂)_(n)—NH—(CH₂)_(m)—NHR⁹;

R³ is H, F or Cl;

each of R⁴, R⁵ and R⁶ is independently H or F;

R⁷ is C₁-C₆ alkyl, CF₃, —SO₂R¹¹, —NH—(CH₂)₂—(NH)_(r)—R⁸, —NH—CH(R⁸R⁹) or a group of the following formula (A):

W is —(CH₂)_(m)—, —CH₂—O—CH₂—, —CH₂—S—CH₂—, —(CH₂)_(r)—S(O)₂—CH₂— or —(CH₂)_(r)—NR⁸—CH₂—;

m is an integer of 1 to 3;

n is 1 or 2;

p is 1 and V is CH; or p is 0 and V is N;

q is 0 or 1;

r is 0 or 1;

R⁸ is H, —SO₂R¹¹, —SO₂CF₃, —COR¹¹, —C(O)OR¹¹, —CON(R⁹)₂ or —(CH₂)_(n)SO₂R¹¹;

R⁹ is H or C₁-C₆ alkyl, each R⁹ being the same or different when two are present;

R¹⁰ is —SO₂R¹¹, —SO₂CF₃, —COR¹¹, —CON(R⁹)₂ or —(CH₂)_(n)SO₂R¹¹; and

R¹¹ is C₁-C₆ alkyl;

or a pharmaceutically acceptable salt thereof.

DETAILED DESCRIPTION OF THE INVENTION

When any group, ring, substituent or moiety defined herein is substituted, it is typically substituted by Q as defined below.

A C₁₋₆ alkyl group or moiety is linear or branched. A C₁₋₆ alkyl group is typically a C₁₋₄ alkyl group, or a C₄₋₆ alkyl group. Examples of C₁₋₆ alkyl groups and moieties include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-pentyl, i-pentyl (i.e. 3-methylbut-1-yl), t-pentyl (i.e. 2-methylbut-2-yl), neopentyl (i.e. 2,2-dimethylpropan-1-yl), n-hexyl, i-hexyl (i.e. 4-methylpentan-1-yl), t-hexyl (i.e. 3-methylpentan-3-yl) and neopentyl (i.e. 3,3-dimethylbutan-1-yl). For the avoidance of doubt, where two alkyl moieties are present in a group, the alkyl moieties may be the same or different. A C₁₋₆ alkyl group is unsubstituted or substituted, typically by one or more groups Q as defined below. For example, a C₁₋₆ alkyl group is unsubstituted or substituted by 1, 2 or 3 groups Q as defined below.

Q is halo, nitro, —CN, OH, C₁₋₆ alkoxy, C₁₋₆ hydroxyalkyl, C₁₋₆ alkylthio, C₁₋₆ haloalkyl, C₁₋₄ haloalkoxy, —CO₂R′″, —NR′″₂, —SR′″, —S(═O)R′″, —S(═O)₂R′″, C₃-C₁₀ cycloalkyl, 5 to 10-membered heterocyclyl, 5- to 12-membered aryl or 5- to 12-membered heteroaryl, wherein each R′″ is independently selected from H, C₁₋₆ alkyl, C₃₋₁₀ cycloalkyl, 5 to 10-membered heterocyclyl, 5- to 12-membered aryl and 5- to 12-membered heteroaryl.

A C₁₋₆ alkoxy group is linear or branched. It is typically a C₁₋₄ alkoxy group, for example a methoxy, ethoxy, propoxy, i-propoxy, n-propoxy, n-butoxy, sec-butoxy or tert-butoxy group. A C₁₋₆ alkoxy group is unsubstituted or substituted, typically by one or more groups Q as defined.

A C₁₋₆ alkylthio group is linear or branched. It is typically a C₁₋₄ alkylthio group, for example a methylthio, ethylthio, propylthio, i-propylthio, n-propylthio, n-butylthio, sec-butylthio or tert-butylthio group. A C₁₋₆ alkyltho group is unsubstituted or substituted, typically by one or more groups Q as defined above.

A halogen or halo group is F, Cl, Br or I. Preferably it is F or Cl. A C₁₋₆ alkyl group substituted by halogen may be denoted “C₁₋₆ haloalkyl”, which means a C₁₋₆ alkyl group as defined above in which one or more hydrogens is replaced by halo. Likewise a C₁₋₆ alkoxy group substituted by halogen may be denoted “C₁₋₆ haloalkoxy”, which means a C₁₋₆ alkoxy group as defined above in which one or more hydrogens is replaced by halo. Typically, C₁₋₆ haloalkyl or C₁₋₆ haloalkoxy is substituted by 1, 2 or 3 said halogen atoms. Haloalkyl and haloalkoxy groups include perhaloalkyl and perhaloalkoxy groups such as —CX₃ and —OCX₃ wherein X is a halogen, for example —CF₃—CCl₃—OCF₃ and —OCCl₃.

A C₁₋₆ hydroxyalkyl group is a C₁₋₆ alkyl group as defined above, substituted by one or more OH groups. Typically, it is substituted by one, two or three OH groups. Preferably, it is substituted by a single OH group.

A 5- to 12-membered aryl group is an aromatic carbocyclic group containing from 5 to 12 carbon atoms, for instance from 6 to 10 carbon atoms, such as 6 or 10 carbon atoms. It is monocyclic or a fused bicyclic ring system in which an aromatic ring is fused to another aromatic carbocyclic ring. Examples of a 5- to 12-membered aryl group include phenyl and naphthyl. When substituted, an aryl group is typically substituted by C₁₋₄ alkyl or a group Q as defined above, for instance by 1, 2 or 3, groups selected from a C₁₋₄ alkyl group and a group Q as defined above.

A C₃₋₁₀ cycloalkyl group is a saturated hydrocarbon ring having from 3 to 10 carbon atoms. A C₃₋₁₀ cycloalkyl group may be, for instance, C₃-C₇ cycloalkyl such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, or cycloheptyl. Typically it is C₃-C₆ cycloalkyl, or C₄-C₆ cycloalkyl, for example cyclobutyl, cyclopentyl or cyclohexyl. In one embodiment it is cyclobutyl. A C₃₋₁₀ cycloalkyl group is unsubstituted or substituted, typically by one or more groups Q as defined above.

A 5- to 12-membered heteroaryl group or moiety is a 5- to 12-membered aromatic heterocyclic group which contains 1, 2, 3, or 4 heteroatoms selected from O, N and S. It is monocyclic or bicyclic. Typically it contains one N atom and 0, 1, 2 or 3 additional heteroatoms selected from O, S and N. It may be, for example, a 5- to 7-membered heteroaryl group, for instance a 5- or 6-membered N-containing heteroaryl group.

Examples include pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, furanyl, thienyl, pyrazolidinyl, pyrrolyl, oxadiazolyl, oxazolyl, isoxazolyl, thiazolyl, thiadiazolyl, imidazolyl and pyrazolyl groups. Furanyl, thienyl, pyridyl and pyrimidyl groups are preferred. When substituted, a heteroaryl group is typically substituted by one or more, e.g. 1, 2 or 3, groups selected from C₁₋₄ alkyl and a group Q as defined above.

A 5- to 10-membered heterocyclyl moiety is a monocyclic or bicyclic non-aromatic, saturated or unsaturated C₅₋₁₀ carbocyclic ring, in which at least one, for example 1, 2 or 3, carbon atoms in the ring are replaced with an atom or group selected from O, S, SO, SO₂, CO and N. Typically, it is a saturated C₅₋₁₀ ring in which 1, 2 or 3 of the carbon atoms in the ring are replaced with an atom or group selected from O, S, SO₂, CO and NH. More typically it is a monocyclic ring, preferably a monocyclic C₅-C₆ ring. Examples include piperidyl, piperidin-2,6-dionyl, piperidin-2-onyl, piperazinyl, morpholinyl, thiomorpholinyl, S,S-dioxothiomorpholinyl, 1,3-dioxolanyl, pyrrolidinyl, imidazol-2-onyl, pyrrolidin-2-onyl, tetrahydrofuranyl and tetrahydropyranyl moieties.

For the avoidance of doubt, although the above definitions of heteroaryl and heterocyclyl groups refer to an “N” atom which can be present in the ring, as will be evident to a skilled chemist the N atom will be protonated (or will carry a substituent as defined above) if it is attached to each of the adjacent ring atoms via a single bond. Such protonated forms are embraced within the present definitions of heteroaryl and heterocyclyl groups.

In one embodiment of the benzimidazoles of formula (I), R¹ is —(CH₂)_(m)—R⁷ in which m is 2 or 3 and R⁷ is —NH—(CH₂)₂—(NH)_(r)—R⁸ wherein r is 0 or 1 and R⁸ is selected from —SO₂Me, —SO₂Et and —SO₂CF₃.

In another embodiment of the benzimidazoles of formula (I), R¹ is —(CH₂)_(m)—R⁷ in which m is 2 or 3 and R⁷ is C₁-C₆ alkyl, CF₃ or —SO₂R¹¹. In this embodiment —SO₂R¹¹ is typically —SO₂Me or —SO₂Et.

In a further embodiment R¹ is —(CH₂)_(m)—R⁷ in which m is 2 or 3 and R⁷ is —NH—CH(R⁸R⁹) wherein R⁸ is —CON(RH₂ or —CONMe₂ and R⁹ is C₁-C₆ alkyl.

In another embodiment R¹ is —(CH₂)_(m)—R⁷ in which m is 2 or 3 and R⁷ is is a group of formula (A) in which p is 1, q is 0, V is CH and W is —(CH₂)_(r)—S(O)₂—CH₂— or —(CH₂)_(r)—NR⁸—CH₂— in which r is 0 and R⁸ is —SO₂Me or —SO₂Et.

In a yet further embodiment R¹ is —(CH₂)_(m)—R⁷ in which m is 2 or 3 and R⁷ is a group of formula (A) in which p is 0, V is N, W is —(CH₂)_(m)— in which m is an integer of 1 to 3, q is 1 and R¹⁰ is —SO₂Me, —SO₂Et, —CONH₂ or —CONMe₂.

In another embodiment R¹ is —(CH₂)_(m)—R⁷ in which m is 2 or 3 and R⁷ is a group of formula (A) in which p is 0, V is N, q is 0 and W is —CH₂O—CH₂—, —CH₂—S—CH₂—, —(CH₂)_(r)—S(O)₂—CH₂— or —(CH₂)_(r)—NR⁸—CH₂— in which r is 0 or 1 and R⁸ is —SO₂Me, —SO₂Et or —COMe.

Alternatively, R¹ is

or in which R⁸ is H, —SO₂R¹¹, —COMe, —C(O)OR¹¹, —CON(R⁹)₂ or —(CH₂)_(n) SO₂R¹¹. In this embodiment —SO₂R¹¹ is typically —SO₂Me or —SO₂Et. —CON(R⁹)₂ is typically —CONH₂ or —CONMe₂. —(CH₂)_(n)SO₂R¹¹ is typically —CH₂CH₂SO₂Me.

When in formula (I) R⁷ is a group of formula (A) and q is 1, the ring substituent R¹⁰ may be bonded to any available ring carbon atom.

When W in formula (A) is —(CH₂)r—NR⁸—CH₂—, q is typically 0.

Examples of the group of formula (A) include the following structures:

Group R² in formula (I) is typically H, F, Cl or —CH₂NH₂. More typically it is Cl or —CH₂NH₂.

The group R⁸ may be, for instance, H, —SO₂Me, —SO₂Et, —SO₂CF₃, —COMe, —CONMe₂, —CONH₂ or —CH₂CH₂SO₂Me.

The group R¹⁰ may be, for instance, —SO₂Me, —SO₂Et, —SO₂CF₃, —COMe, —CONMe₂, —CONH₂ or —CH₂CH₂SO₂Me.

In one embodiment of formula (I), the substituents are as follows:

-   -   R¹ is —(CH₂)_(m)—R⁷,

-   -   R² is H, halo, —(CH₂)_(m)—NH₂, —(CH₂)_(n)—C(═NH)—NH₂ or         —(CH₂)_(n)—NH—(CH₂)_(m)—NHR⁹;     -   R³ is H, F or Cl;     -   each of R⁴, R⁵ and R⁶ is independently H or F;     -   R⁷ is C₁-C₆ alkyl, CF₃, —NH—(CH₂)₂—(NH)_(r)—R⁸, —NH—(CHR⁸R⁹) or         a group of the following formula (A):

-   -   W is —(CH₂)_(m)—, —CH₂—O—CH₂—, —CH₂—S—CH₂—,         —(CH₂)_(r)—S(O)₂—CH₂— or —(CH₂)_(r)—NR⁸—CH₂—;     -   m is an integer of 1 to 3;     -   n is 1 or 2;     -   p is 1 and V is CH; or p is 0 and V is N;     -   q is 0 or 1;     -   r is 0 or 1;     -   R⁸ is H, —SO₂Me, —SO₂Et, —SO₂CF₃, —COMe, —CONMe₂, —CONH₂ or         —CH₂CH₂SO₂Me;     -   R⁹ is H or C₁-C₆ alkyl; and     -   R¹⁰ is —SO₂Me, —SO₂Et, —SO₂CF₃, —COMe, —CONMe₂, —CONH₂ or         —CH₂CH₂SO₂Me.

Specific compounds of the invention include the following:

-   1-{[5-Chloro-1-(4,4,4-trifluorobutyl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one; -   1-({5-Chloro-1-[3-(4-methanesulfonylpiperazin-1-yl)propyl]-1H-1,3-benzodiazol-2-yl}methyl)-3,3-difluoro-2,3-dihydro-1H-indol-2-one; -   1-[(5-Chloro-1-{3-[(2-methanesulfonylethyl)amino]propyl}-1H-1,3-benzodiazol-2-yl)methyl]-3,3-difluoro-2,3-dihydro-1H-indol-2-one; -   1-({5-Chloro-1-[3-(3-methanesulfonylpyrrolidin-1-yl)propyl]-1H-1,3-benzodiazol-2-yl}methyl)-3,3-difluoro-2,3-dihydro-1H-indol-2-one; -   1-{[5-Chloro-1-(3-methanesulfonylpropyl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one; -   tert-Butyl     4-{5-chloro-2-[(3,3-difluoro-2-oxo-2,3-dihydro-1H-indol-1-yl)methyl]-1H-1,3-benzodiazol-1-yl}piperidine-1-carboxylate; -   1-{[5-Chloro-1-(piperidin-4-yl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one; -   1-{[5-Chloro-1-(1-methanesulfonylpiperidin-4-yl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one; -   1-({5-Chloro-1-[1-(ethanesulfonyl)piperidin-4-yl]-1H-1,3-benzodiazol-2-yl}methyl)-3,3-difluoro-2,3-dihydro-1H-indol-2-one; -   1-{[5-Chloro-1-(oxan-4-yl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one; -   1-{[5-Chloro-1-(oxan-4-yl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3,6-trifluoro-2,3-dihydro-1H-indol-2-one; -   1-{[5-Chloro-1-(oxan-4-yl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3,7-trifluoro-2,3-dihydro-1H-indol-2-one; -   1-{[5-(Aminomethyl)-1-(3-methylbutyl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one; -   1-{[5-(Aminomethyl)-1-(3-methylbutyl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3,4-trifluoro-2,3-dihydro-1H-indol-2-one; -   1-{[5-(Aminomethyl)-1-(3-methylbutyl)-1H-1,3-benzodiazol-2-yl]methyl}-4-chloro-3,3-difluoro-2,3-dihydro-1H-indol-2-one; -   1-{[5-(Aminomethyl)-1-(3-methylbutyl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3,5-trifluoro-2,3-dihydro-1H-indol-2-one; -   and the pharmaceutically acceptable salts thereof.

The compounds of the invention may contain asymmetric or chiral centres, and therefore exist in different stereoisomeric forms. It is intended that all stereoisomeric forms of the compounds of the invention, including but not limited to, diastereomers, enantiomers and atropisomers, as well as mixtures thereof such as racemic mixtures, form part of the present invention. Compounds of Formula (I) containing one or more chiral centre may be used in enantiomerically or diastereoisomerically pure form, or in the form of a mixture of isomers.

The present invention embraces all geometric and positional isomers of compounds of the invention as defined above. For example, if a compound of the invention incorporates a double bond or a fused ring, the cis- and trans-forms, as well as mixtures thereof, are embraced within the scope of the invention. Both the single positional isomers and mixture of positional isomers are also within the scope of the present invention.

The compounds of the present invention may exist in unsolvated as well as solvated forms with pharmaceutically acceptable solvents such as water, ethanol, and the like, and it is intended that the invention embrace both solvated and unsolvated forms.

The compounds of the present invention may exist in different tautomeric forms, and all such forms are embraced within the scope of the invention. The term “tautomer” or “tautomeric form” refers to structural isomers of different energies which are interconvertible via a low energy barrier. For example, proton tautomers (also known as prototropic tautomers) include interconversions via migration of a proton, such as keto-enol tautomerizations. Valence tautomers include interconversions by reorganization of some of the bonding electrons.

Compounds of the invention can be prepared by synthetic methods described in the Examples that follow, or by analogy with such methods.

A benzimidazole of formula (I) can be converted into a pharmaceutically acceptable salt thereof, and a salt can be converted into the free compound, by conventional methods. For instance, a benzimidazole of formula (I) can be contacted with a pharmaceutically acceptable acid to form a pharmaceutically acceptable salt. A pharmaceutically acceptable salt is a salt with a pharmaceutically acceptable acid or base.

Pharmaceutically acceptable acids include both inorganic acids such as hydrochloric, sulphuric, phosphoric, diphosphoric, hydrobromic or nitric acid and organic acids such as citric, fumaric, maleic, malic, ascorbic, succinic, tartaric, benzoic, acetic, methanesulphonic, ethanesulphonic, benzenesulphonic or p-toluenesulphonic acid. Pharmaceutically acceptable bases include alkali metal (e.g. sodium or potassium) and alkali earth metal (e.g. calcium or magnesium) hydroxides and organic bases such as alkyl amines, aralkyl amines and heterocyclic amines.

Compounds of the present invention have been found in biological tests to be inhibitors of respiratory syncytial virus (RSV). The compounds are therefore therapeutically useful. Accordingly, the present invention further provides a compound which is a benzimidazole of formula (I), as defined above, or a pharmaceutically acceptable salt thereof, for use in a method of treating the human or animal body by therapy. The invention also provides a compound of the invention as defined above for use in a method treating or preventing an RSV infection. Still further, the present invention provides the use of a compound of the invention as defined above in the manufacture of a medicament for use in treating or preventing an RSV infection. A subject suffering from or susceptible to an RSV infection may thus be treated by a method comprising the administration thereto of a compound of the invention as defined above. The condition of the subject may thereby be improved or ameliorated.

The RSV infection is typically a respiratory tract infection. The RSV infection may be an infection in a child, for instance a child under ten years of age or an infant under two years of age. In one embodiment the invention provides a compound as defined above for use in treating or preventing an RSV infection in paediatric patients. Alternatively the infection may be an infection in a mature or elderly adult, for instance an adult over 60 years of age, an adult over 70 years of age, or an adult over 80 years of age. The invention further provides a compound for use in treating or preventing an RSV infection in geriatric patients.

The RSV infection may be an infection in an immunocompromised individual or an individual suffering from COPD or CHF. In another embodiment, the RSV infection is an infection in a non-compromised individual, for instance an individual who is otherwise healthy.

A compound of the present invention can be administered in a variety of dosage forms, for example orally such as in the form of tablets, capsules, sugar- or film-coated tablets, liquid solutions or suspensions or parenterally, for example intramuscularly, intravenously or subcutaneously. The compound may therefore be given by injection, infusion, or by inhalation or nebulaisation. The compound is preferably given by oral administration.

The dosage depends on a variety of factors including the age, weight and condition of the patient and the route of administration. Daily dosages can vary within wide limits and will be adjusted to the individual requirements in each particular. Typically, however, the dosage adopted for each route of administration when a compound is administered alone to adult humans is 0.0001 to 650 mg/kg, most commonly in the range of 0.001 to 10 mg/kg, body weight, for instance 0.01 to 1 mg/kg. Such a dosage may be given, for example, from 1 to 5 times daily. For intravenous injection a suitable daily dose is from 0.0001 to 1 mg/kg body weight, preferably from 0.0001 to 0.1 mg/kg body weight. A daily dosage can be administered as a single dosage or according to a divided dose schedule.

A unit dose form such as a tablet or a capsule will usually contain 1-250 mg of active ingredient. For example, a compound of formula (I) could be administered to a human patient at a dose of between 100-250 mg either once a day, twice or three times a day. For example, a compound of formula (I) could be administered to a human patient at a dose of between 100-250 mg either once a day, twice or three times a day.

The compounds of formula (I) and pharmaceutically acceptable salts thereof may be used on their own. Alternatively, they may be administered in the form of a pharmaceutical composition. The present invention therefore also provides a pharmaceutical composition comprising a compound of formula (I) or a pharmaceutically acceptable salt thereof as hereinbefore defined, in association with a pharmaceutically acceptable adjuvant, diluent or carrier. Conventional procedures for the selection and preparation of suitable pharmaceutical formulations are described in, for example, “Pharmaceuticals—The Science of Dosage Form Designs”, M. E. Aulton, Churchill Livingstone, 1988.

Depending on the mode of administration, the pharmaceutical composition will preferably comprise from 0.05 to 99% w (percent by weight), more preferably from 0.05 to 80% w, still more preferably from 0.10 to 70% w, and even more preferably from 0.10 to 50% w, of active ingredient, all percentages by weight being based on total composition.

The invention further provides a process for the preparation of a pharmaceutical composition of the invention which comprises mixing a compound of formula (I) or a pharmaceutically acceptable salt thereof as hereinbefore defined with a pharmaceutically acceptable adjuvant, diluent or carrier.

The compounds of the invention may be administered in a variety of dosage forms. Thus, they can be administered orally, for example as tablets, troches, lozenges, aqueous or oily suspensions, solutions, dispersible powders or granules. The compounds of the invention may also be administered parenterally, whether subcutaneously, intravenously, intramuscularly, intrasternally, transdermally, by infusion techniques or by inhalation or nebulisation. The compounds may also be administered as suppositories.

Solid oral forms of the pharmaceutical composition of the invention may contain, together with the active compound, diluents, e.g. lactose, dextrose, saccharose, cellulose, corn starch or potato starch; lubricants, e.g. silica, talc, stearic acid, magnesium or calcium stearate, and/or polyethylene glycols; binding agents; e.g. starches, arabic gums, gelatin, methylcellulose, carboxymethylcellulose or polyvinyl pyrrolidone; disaggregating agents, e.g. starch, alginic acid, alginates or sodium starch glycolate; effervescing mixtures; dyestuffs; sweeteners; wetting agents, such as lecithin, polysorbates, laurylsulfates; and, in general, non toxic and pharmacologically inactive substances used in pharmaceutical formulations. Such pharmaceutical preparations may be manufactured in known manner, for example, by means of mixing, granulating, tableting, sugar coating, or film coating processes.

Liquid dispersions for oral administration may be syrups, emulsions and suspensions. The syrups may contain as carriers, for example, saccharose or saccharose with glycerine and/or mannitol and/or sorbitol.

Suspensions and emulsions may contain as carrier, for example a natural gum, agar, sodium alginate, pectin, methylcellulose, carboxymethylcellulose, or polyvinyl alcohol. The suspension or solutions for intramuscular injections may contain, together with the active compound, a pharmaceutically acceptable carrier, e.g. sterile water, olive oil, ethyl oleate, glycols, e.g. propylene glycol, and if desired, a suitable amount of lidocaine hydrochloride. Further suitable carriers for suspensions include sterile water, hydroxypropylmethyl cellulose (HPMC), polysorbate 80, polyvinylpyrrolidone (PVP), aerosol AOT (i.e. sodium 1,2-bis(2-ethylhexoxycarbonyl)ethanesulphonate), pluronic F127 and/or captisol (i.e. sulfobutylether-beta-cyclodextrin).

The compounds of the invention may, for example, be formulated as aqueous suspensions in a carrier selected from:

(i) 0.5% w/v hydroxypropylmethyl cellulose (HPMC)/0.1% w/v polysorbate 80;

(ii) 0.67% w/v polyvinylpyrrolidone (PVP)/0.33% w/v aerosol AOT (sodium 1,2-bis(2-ethylhexoxycarbonyl)ethanesulphonate);

(iii) 1% w/v pluronic F 127; and

(iv) 0.5% w/v polysorbate 80.

The carriers may be prepared by standard procedures known to those of skill in the art. For example, each of the carriers (i) to (iv) may be prepared by weighing the required amount of excipient into a suitable vessel, adding approximately 80% of the final volume of water and magnetically stirring until a solution is formed. The carrier is then made up to volume with water. The aqueous suspensions of compounds of formula I may be prepared by weighing the required amount of a compound of formula I into a suitable vessel, adding 100% of the required volume of carrier and magnetically stirring.

Solutions for injection or infusion may contain as carrier, for example, sterile water or preferably they may be in the form of sterile, aqueous, isotonic saline solutions.

The compounds of the invention may also be administered in conjunction with other compounds used for the treatment of viral infections. Thus, the invention further relates to combination therapies wherein a compound of the invention, or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition or formulation comprising a compound of the invention, is administered concurrently or sequentially or as a combined preparation with another therapeutic agent or agents, for the treatment or prevention of a viral infection, particularly infection by RSV.

Herein, where the term “combination” is used it is to be understood that this refers to simultaneous, separate or sequential administration. In one aspect of the invention “combination” refers to simultaneous administration. In another aspect of the invention “combination” refers to separate administration. In a further aspect of the invention “combination” refers to sequential administration. Where the administration is sequential or separate, the delay in administering the second component should not be such as to lose the beneficial effect of the combination.

Suitable therapeutic agents for use in the combination therapies include

(i) RSV nucleocapsid (N)-protein inhibitors;

(ii) other RSV protein inhibitors, such as those that inhibit the phosphoprotein (P) protein and large (L) protein;

(iii) anti-RSV monoclonal antibodies, such as the F-protein antibodies;

(iv) immunomodulating toll-like receptor compounds;

(v) other respiratory virus anti-virals, such as anti-influenza and anti-rhinovirus compounds; and/or

(vi) anti-inflammatory compounds.

The RSV nucleocapsid (N)-protein plays a pivotal role in viral transcription and replication, mediating the interaction between the genomic RNA and the virally encoded RNA-dependent RNA polymerase. The RSV P- and L-proteins are components of RSV's virally encoded RNA-dependent RNA polymerase.

According to a further aspect of the invention, there is provided a compound of the formula (I) or a pharmaceutically acceptable salt thereof as hereinbefore defined in combination with one or more of the therapeutic agents listed as (i) to (vi) above for use in the treatment of RSV.

The following Examples illustrate the invention. They do not however, limit the invention in any way.

EXAMPLES

Reagents were obtained from commercial sources and were used without further purification. All temperatures are in ° C. TLC was performed on aluminium backed silica gel plates with fluorescence indicator at 254 nM (median pore size 60 Å). Flash column chromatography was performed using a Biotage Isolera One system using KP-Sil, Ultra or KP-NH columns. NMR spectra were recorded on a 400 MHz spectrometer at ambient probe temperature (nominal 295K). Chemical shifts (δ) are given in ppm and calibrated by using the residual peak of the solvent as the internal standard (CDCl₃, δ_(H)=7.26 ppm, δ_(C)=77.16 ppm; DMSO-d₆, δ_(H)=2.50 ppm, δ_(C)=39.52 ppm). Coupling constants are given in Hertz (Hz). LRMS were recorded using an Advion Plate Express expression^(L) compact mass spectrometer equipped with either an APCI or ESI ion source.

Abbreviations

DMSO Dimethyl sulfoxide EtOAc Ethyl acetate EtOH Ethanol h Hour(s) iPrOH Isopropanol LRMS Low resolution mass spectrometry MeCN Acetonitrile MeOH Methanol rt room temperature TFA Trifluoroacetic acid

Preparatory Examples 1A: 3,3-Difluoro-2,3-dihydro-1H-indol-2-one

Prepared by adaptation of the deoxyfluorination procedure reported by Singh et al, J Org. Chem. 2001 Sep. 1; 66(19):6263-7. Isatin (3.05 g, 20.72 mmol) was dissolved in anhydrous CH₂Cl₂ (50 mL) under an inert atmosphere and cooled to 0° C. Diethylaminosulfur trifluoride (8.29 mL, 62.74 mmol) was added, and the reaction stirred for 23 h at rt. After cooling to 0° C., the reaction was cautiously quenched with saturated aqueous NaHCO₃ solution until no further effervescence was observed, and extracted with CH₂Cl₂ (3×50 mL). The combined organic extracts were washed successively with saturated aqueous NaHCO₃ solution, water and brine (50 mL each), dried (MgSO₄) and the solvent removed under reduced pressure. Purification by flash chromatography (SiO₂; EtOAc/heptane; 10-32%) afforded a yellow solid, which was triturated with heptane to afford the product as an off-white solid (2.637 g, 75%). ¹H NMR (400 MHz, CDCl₃): δ 7.95 (br s, 1H), 7.57-7.53 (m, 1H), 7.48-7.42 (m, 1H), 7.17 (t, J=7.7 Hz, 1H), 6.96-6.92 (m, 1H). LRMS (APCI-) m/z 167.9 [M−H]⁻

The following intermediate compounds were prepared by the same general deoxyfluorination procedure.

TABLE 1 Examples prepared via general deoxyfluorination procedure

Preparatory ¹H NMR δ LRMS Example Name R¹ (400 MHz, CDCl₃) AP-CI− 1B 3,3,4-Trifluoro-2,3- 4-F 7.95 (br s, 1H), 7.48-7.41 (m, 1H), 185.9 dihydro-1H-indol-2-one 6.87-6.82 (m, 1H), 6.76-6.72 (m, 1H) [M − H]⁻ 1C 4-Chloro-3,3-difluoro-2,3- 4-Cl 8.06 (br s, 1H), 7.41-7.35 (m, 1H), 201.9 dihydro-1H-indol-2-one 7.11 (d, J = 8.3 Hz, 1H), 6.86-6.82 [M − H]⁻ (m, 1H) 1D 3,3,5-Trifluoro-2,3- 5-F 8.05 (br s, 1H), 7.32-7.27 (m, 1H), 185.9 dihydro-1H-indol-2-one 7.21-7.14 (m, 1H), 6.94-6.88 (m, 1H) [M − H]⁻ 1E 3,3,6-Trifluoro-2,3- 6-F 8.19 (br s, 1H), 7.57-7.51 (m, 1H), 185.8 dihydro-1H-indol-2-one 6.88-6.82 (m, 1H), 6.72-6.68 (m, 1H) [M − H]⁻ 1F 3,3,7-Trifluoro-2,3- 7-F 7.91 (br s, 1H), 7.39-7.35 (m, 1H), 185.9 dihydro-1H-indol-2-one 7.28-7.22 (m, 1H), 7.19-7.12 (m, 1H) [M − H]⁻

2A: 4-Chloro-N-(3,3-diethoxypropyl)-2-nitroaniline

N,N-Diisopropylethylamine (3.397 mL, 19.5 mmol) followed by 3,3-diethoxypropan-1-amine (3.154 mL, 19.5 mmol) were added to a solution of 4-chloro-1-fluoro-2-nitrobenzene (1.765 mL, 15 mmol), in iPrOH (35 mL) and heated at 80° C. for 4.5 h. After cooling to rt, the reaction mixture was diluted with EtOAc (100 mL), washed successively with H₂O (acidified to ˜pH 6 with 0.01 M aqueous HCl, 4×) and brine (1×, 100 mL each), dried (MgSO4) and the solvent removed under reduced pressure to afford the crude product as an orange solid (4.308 g, 97%). ¹H NMR (400 MHz, CDCl₃): δ 8.29 (br s, 1H), 8.17 (d, J=2.6 Hz, 1H), 7.37 (ddd, J=9.2, 2.6, 0.6 Hz, 1H), 6.83 (d, J=9.2 Hz, 1H), 4.65 (t, J=5.0 Hz, 1H), 3.76-3.65 (m, 2H), 3.59-3.49 (m, 2H), 3.44-3.37 (m, 2H), 2.07-2.01 (m, 2H), 1.24 (t, J=7.0 Hz, 6H). LRMS (ESI+) m/z 324.9 [M+Na]⁺

2B: tert-Butyl 4-[(4-chloro-2-nitrophenyl)amino]piperidine-1-carboxylate

Prepared by an analogous procedure to intermediate 2A. ¹H NMR (400 MHz, CDCl₃): δ 8.19 (d, J=2.6 Hz, 1H), 8.06 (d, J=7.4 Hz, 1H), 7.40-7.35 (m, 1H), 6.84 (d, J=9.3 Hz, 1H), 4.09-3.95 (m, 2H), 3.69-3.60 (m, 1H), 3.09-2.98 (m, 2H), 2.09-2.00 (m, 2H), 1.57-1.50 (m, 2H), 1.47 (s, 9H). LRMS (APCI-) m/z 353.9 [M−H]⁻

3A: 4-Chloro-N¹-(3,3-diethoxypropyl)benzene-1,2-diamine

In a 250 mL round-bottom pressure flask 4-chloro-N-(3,3-diethoxypropyl)-2-nitroaniline (intermediate 2A) (4.050 g, 13.38 mmol) was dissolved in EtOH (100 mL) and platinum on carbon (5 wt. % loading, 393 mg) added. The reaction vessel was filled with hydrogen to a pressure of 50 psi and stirred for 3 h. The reaction mixture was filtered through a glass micro fiber filter, washing with EtOH and the solvent removed under reduced pressure. Purification by flash chromatography [SiO₂;CH₂Cl₂/(CH₂Cl₂:EtOH:NH₄OH 80:20:1); 0-25%] afforded the title compound as a dark brown oil (3.440 g, 94%). ¹H NMR (400 MHz, CDCl₃): δ 6.74 (dd, J=8.4, 2.4 Hz, 1H), 6.67 (d, J=2.4 Hz, 1H), 6.53 (d, J=8.4 Hz, 1H), 4.65 (t, J=5.4 Hz, 1H), 3.83-3.64 (m, 3H), 3.57-3.47 (m, 2H), 3.40 (br s, 2H), 3.17 (t, J=6.4 Hz, 2H), 2.02-1.96 (m, 2H), 1.23 (t, J=7.0 Hz, 6H). LRMS (ESI+) m/z 273.1 [M+Na]⁺

3B tert-Butyl 4-[(2-amino-4-chlorophenyl)amino]piperidine-1-carboxylate

Prepared by an analogous procedure to intermediate 3A from intermediate 2B. ¹H NMR (400 MHz, CDCl₃): δ 6.75-6.69 (m, 2H), 6.57 (d, J=8.3 Hz, 1H), 4.03 (br s, 2H), 3.54-3.26 (m, 3H), 3.00-2.86 (m, 2H), 2.04-1.96 (m, 2H), 1.42 (s, 9H), 1.42-1.30 (m, 2H). LRMS (ESI+) m/z 326.3 [M+H]⁺

4A: 5-Chloro-2-(chloromethyl)-1-(3,3-diethoxypropyl)-1H-1,3-benzodiazole

A solution of intermediate 2A (2.524 g, 9.27 mmol) and 2-chloro-1,1,1-triethoxyethane (2.499 mL, 18.54 mmol) in EtOH (90 mL) was heated at 75° C. for 7.5 h, then stirred at rt for 12 h. The volatiles were removed under reduced pressure and the reaction mixture purified by flash chromatography (SiO₂; EtOAc/petroleum ether 60/80; 0-60%) to give the product as a brown solid (1.537 g, 50%). ¹H NMR (400 MHz, CDCl₃): δ 7.74-7.72 (m, 1H), 7.34-7.26 (m, 2H), 4.87 (s, 2H), 4.48 (t, J=5.0 Hz, 1H), 4.37 (t, J=7.1 Hz, 2H), 3.68-3.58 (m, 2H), 3.49-3.39 (m, 2H), 2.21-2.14 (m, 2H), 1.20 (t, J=7.1 Hz, 6H). LRMS (APCI+) m/z 331.1 [M+H]⁺

4B: tert-Butyl 4-[5-chloro-2-(chloromethyl)-1H-1,3-benzodiazol-1-yl]piperidine-1-carboxylate

Prepared by an analogous procedure to intermediate 4A from intermediate 3B. ¹H NMR (400 MHz, CDCl₃): δ 7.73 (d, J=1.9 Hz, 1H), 7.42 (d, J=8.7 Hz, 1H), 7.24 (dd, J=8.8, 2.0 Hz, 1H), 4.85 (s, 2H), 4.52-4.27 (m, 3H), 2.98-2.81 (m, 2H), 2.46-2.31 (m, 2H), 2.03-1.93 (m, 2H), 1.52 (s, 9H). LRMS (APCI+) m/z 383.9 [M+H]⁺

5A: 1-{[5-Chloro-1-(3,3-diethoxypropyl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one

A solution of intermediate 4A (293 mg, 0.885 mmol), 3,3-di-fluoro-2,3-dihydro-1H-indol-2-one (intermediate 1A, 150 mg, 0.885 mmol) and K₂CO₃ (300 mg, 2.167 mmol) in anhydrous MeCN (6 mL) was heated under an inert atmosphere at 70° C. for 1 h 45 min. After cooling to rt, the reaction was diluted with EtOAc (30 mL) and washed with H₂O (10 mL). The aqueous layers were extracted with EtOAc (2×20 mL), the combined organic extracts washed successively with H₂O and brine (10 mL each), dried (MgSO₄) and the solvent removed under reduced pressure. Purification by flash chromatography (SiO₂, SiO₂, 12-65% EtOAc in heptane) afforded the product as a white solid (303 mg, 74%). ¹H NMR (400 MHz, CDCl₃): δ 7.74 (dd, J=1.9, 0.6 Hz, 1H), 7.56-7.51 (m, 2H), 7.49-7.43 (m, 1H), 7.33-7.29 (m, 1H), 7.29-7.24 (m, 1H), 7.17 (t, J=7.7, 1H), 5.23 (s, 2H), 4.48 (t, J=5.3 Hz, 1H), 4.35 (t, J=7.0 Hz, 2H), 3.66-3.55 (m, 2H), 3.48-3.39 (m, J, 2H), 2.04-1.97 (m, 2H), 1.17 (t, J=7.1 Hz, 6H). LRMS (APCI+) m/z 463.9 [M+H]⁺

The following 5-aminomethylene intermediate compounds were prepared by the same general procedure described for intermediate 5A from tert-butyl N-{[2-(chloromethyl)-1-(3-methylbutyl)-1H-1,3-benzodiazol-5-yl]methyl}carbamate, denoted intermediate 4C (see Table 2 below).

TABLE 2 5-Aminomethylene intermediates prepared by general procedure

Preparatory ¹H NMR δ Example Name R (400 MHz, CDCl₃) LRMS AP-CI+ 5B tert-butyl N-({2-[(3,3- H 7.67 (br s, 1H), 7.57-7.49 (m, 498.8 [M + H]⁺ difluoro-2-oxo-2,3-dihydro- 2H), 7.47-7.41 (m, 1H), 7.30- 1H-indol-1-yl)methyl]-1-(3- 7.22 (m, 2H), 7.16 (t, J = 7.7 methylbutyl)-1H-1,3- Hz, 1H), 5.20 (s, 2H), 4.88 (br s, benzodiazol-5- 1H), 4.43 (d, J = 5.9 Hz, 2H), yl}methyl)carbamate 4.28-4.16 (m, 2H), 1.79-1.67 (m, 1H), 1.53-1.45 (m, 11H), 0.97 (d, J = 6.6 Hz, 6H) 5C tert-butyl N-{[1-(3- 4-F 7.66 (s, 1H), 7.47-7.36 (m, 2H), 517.1 [M + H]⁺ methylbutyl)-2-[(3,3,4- 7.31-7.25 (m, 2H), 6.84 (dd, J = trifluoro-2-oxo-2,3-dihydro- 8.9, 7.9 Hz, 1H), 5.19 (s, 2H), 1H-indol-1-yl)methyl]-1H- 4.88 (br s, 1H), 4.46-4.39 (m, 1,3-benzodiazol-5- 2H), 4.24-4.17 (m, 2H), 1.79- yl]methyl}carbamate 1.72 (m, 1H), 1.55-1.44 (m, 11H), 1.01-0.95 (m, 6H) 5D tert-butyl N-({2-[(4-chloro- 4-Cl 7.66 (s, 1H), 7.49 (d, J = 8.0 Hz, 533.1 [M + H]⁺ 3,3-difluoro-2-oxo-2,3- 1H), 7.39-7.34 (m, 1H), 7.30- dihydro-1H-indol-1- 7.23 (m, 2H), 7.09 (d, J = 8.2 yl)methyl]-1-(3-methylbutyl)- Hz, 1H), 5.19 (s, 2H), 4.88 (br s, 1H-1,3-benzodiazol-5- 1H), 4.46-4.38 (m, 2H), 4.25- yl}methyl)carbamate 4.17 (m, 2H), 1.79-1.68 (m, 1H), 1.55-1.44 (m, 11H), 1.01- 0.96 (m, 6H) 5E tert-butyl N-{[1-(3- 5-F 7.66 (s, 1H), 7.57 (dd, J = 8.7, 517.2 [M + H]⁺ methylbutyl)-2-[(3,3,5- 3.8 Hz, 1H), 7.36-7.23 (m, 3H), trifluoro-2-oxo-2,3-dihydro- 7.18-7.12 (m, 1H), 5.19 (s, 2H), 1H-indol-1-yl)methyl]-1H- 4.88 (br s, 1H), 4.47-4.38 (m, 1,3-benzodiazol-5- 2H), 4.24-4.17 (m, 2H), 1.79- yl]methyl}carbamate 1.67 (m, 1H), 1.54-1.44 (m, 11H), 1.01-0.95 (m, 6H).

6A: 3-{5-Chloro-2-[(3,3-difluoro-2-oxo-2,3-dihydro-1H-indol-1-yl)methyl]-1H-1,3-benzodiazol-1-yl}propanal

HCl (2 M aqueous solution, 3 mL) was added to a solution of intermediate 5A (288 mg, 0.621 mmol) in tetrahydrofuran (5 m) and stirred at rt for 7 h. The reaction was quenched with saturated aqueous NaHCO₃ solution (˜10 mL) and extracted with EtOAc (3×15 mL). The combined organic extracts were washed with brine (15 mL each), dried (MgSO₄) and the solvent removed under reduced pressure. Purification by flash chromatography (SiO₂, 20-100% EtOAc in heptane) afforded a white solid (216 mg, 89%). ¹H NMR (400 MHz, CDCl₃): δ 9.74 (s, 1H), 7.76-7.72 (m, 1H), 7.57-7.45 (m, 3H), 7.35-7.25 (m, 2H), 7.19 (t, J=7.6 Hz, 1H), 5.32 (s, 2H), 4.61 (t, J=6.5 Hz, 2H), 2.95 (t, J=6.4 Hz, 1H). LRMS (APCI+) m/z 390.1 [M+H]⁺

Examples 1: 1-{[5-Chloro-1-(4,4,4-trifluorobutyl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one

Prepared by an analogous procedure to 5A from 1A and 5-chloro-2-(chloromethyl)-1-(4,4,4-trifluorobutyl)-1H-1,3-benzodiazole. ¹H NMR (400 MHz, CDCl₃): δ 7.78-7.77 (m, 1H), 7.59-7.45 (m, 3H), 7.33-7.23 (m, 2H), 7.19 (t, J=7.6 Hz, 1H), 5.20 (s, 2H), 4.34-4.28 (m, 2H), 2.27-2.14 (m, 2H), 1.95-1.85 (m, 2H). LRMS (APCI+) m/z 444.0 [M+H]⁺

2: 1-({5-Chloro-1-[3-(4-methanesulfonylpiperazin-1-yl)propyl]-1H-1,3-benzodiazol-2-yl}methyl)-3,3-difluoro-2,3-dihydro-1H-indol-2-one

1-(Methylsulfonyl)piperazine (26 mg, 0.156 mmol) was added to a solution of intermediate 6A (61 mg, 0.156 mmol) in 1,2-dichloroethane (3 mL) and stirred at rt for 7.5 h. NaBH(OAc)₃ (46 mg, 0.219 mmol) was then added and the reaction stirred for 18 h at rt. The reaction was quenched with NaOH (1 M aqueous solution, 5 mL), extracted with CH₂Cl₂ (4×10 mL), the combined organic extracts washed with brine (5 mL), dried (Na₂SO₄) and the solvent removed under reduced pressure. Purification by flash chromatography (SiO₂, 50-100% EtOAc in heptane, then 0-5% MeOH in CH₂Cl₂ with 1% NH₄OH) afforded the product as a white solid (50 mg, 60%). ¹H NMR (400 MHz, DMSO-d₆): δ 7.78-7.74 (m, 1H), 7.68-7.64 (m, 2H), 7.61-7.55 (m, 1H), 7.32-7.23 (m, 3H), 5.36 (s, 2H), 4.36 (t, J=6.8 Hz, 2H), 3.11-3.04 (m, 4H), 2.86 (s, 3H), 2.44-2.37 (m, 4H), 2.34-2.26 (m, 2H), 2.01-1.91 (m, 2H). LRMS (APCI+) m/z 538.2 [M+H]⁺

The following compounds of the invention were prepared with intermediate 6A by the general reductive amination procedure described for the compound of Example 2.

TABLE 3 Examples prepared via reductive amination

¹H NMR δ LRMS Example Name R¹ (400 MHz, DMSO-d₆) AP-CI+ 3 1-[(5-Chloro-1-{3-[(2- methanesulfonylethyl) amino]propyl}-1H-1,3- benzodiazol-2-yl)methyl]- 3,3-difluoro-2,3-dihydro- 1H-indol-2-one

7.78-7.74 (m, 1H), 7.67-7.61 (m, 2H), 7.60-7.55 (m, 1H), 7.32-7.19 (m, 3H), 5.35 (s, 2H), 4.41-4.32 (m, 2H), 3.24 (t, J = 6.7 Hz, 2H), 3.01 (s, 3H), 2.91 (t, J = 6.7 Hz, 2H), 2.06 (s, 1H), 1.94-1.85 (m, 2H) 496.1 [M + H]⁺ 4 1-({5-Chloro-1-[3-(3- methanesulfonylpyrrolidin- 1-yl)propyl]-1H-1,3- benzodiazol-2-yl}methyl)- 3,3-difluoro-2,3-dihydro- 1H-indol-2-one

7.78-7.73 (m, 1H), 7.68-7.63 (m, 1H), 7.60-7.54 (m, 1H), 7.29-7.22 (m, 3H), 5.40-5.30 (m, 2H), 4.39- 4.33 (m, 2H), 3.84-3.75 (m, 1H), 2.94 (s, 3H), 2.89-2.84 (m, 1H), 2.79-2.73 (m, 1H), 2.64-2.58 (m, 1H), 2.38-2.31 (m, 2H), 2.15-2.08 (m, 2H), 2.01-1.93 (m, 2H) 523.1 [M + H]⁺

5: 1-{[5-Chloro-1-(3-methanesulfonylpropyl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one

Prepared by an analogous procedure to 5A from 1A and 5-chloro-2-(chloromethyl)-1-(3-methanesulfonylpropyl)-1H-1,3-benzodiazole. ¹H NMR (400 MHz, DMSO-d₆): δ 7.79-7.74 (m, 1H), 7.70 (d, J=8.8 Hz, 1H), 7.66 (d, J=2.0 Hz, 1H), 7.61-7.55 (m, 1H), 7.32 (dd, J=8.7, 2.0 Hz, 1H), 7.28-7.23 (m, 2H), 5.34 (s, 2H), 4.47 (t, J=7.5 Hz, 2H), 3.29-3.23 (m, 2H), 3.02 (s, 3H), 2.27-2.17 (m, 2H). LRMS (APCI+) m/z 453.7 [M+H]⁺

6: tert-Butyl 4-{5-chloro-2-[(3,3-difluoro-2-oxo-2,3-dihydro-1H-indol-1-yl)methyl]-1H-1,3-benzodiazol-1-yl}piperidine-1-carboxylate

Prepared by an analogous procedure to 5A from 1A and 4B. ¹H NMR (400 MHz, CDCl₃): δ 7.76 (d, J=2.0, 1H), 7.55-7.38 (m, 4H), 7.21 (dd, J=8.8, 2.0 Hz, 1H), 7.19-7.15 (m, 1H), 5.24 (s, 2H), 4.70-4.58 (m, 1H), 4.40-4.18 (m, 2H), 2.97-2.83 (m, 2H), 2.37-2.21 (m, 2H), 1.70-1.60 (m, 2H), 1.50 (s, 9H). LRMS (APCI+) m/z 516.6 [M+H]⁺

7: 1-{[5-Chloro-1-(piperidin-4-yl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one

TFA (2 mL) was added to a cooled solution (0° C.) of compound 6 (549 mg, 1.06 mmol) in CH₂Cl₂ (8 mL) and stirred at rt for 2 h. The reaction was cooled to 0° C., quenched with saturated aqueous NaHCO₃ solution and extracted with CH₂Cl₂ (3×20 mL). The combined organic extracts were washed with brine (25 mL), dried (Na₂SO₄) and the solvent removed under reduced pressure. Purification by flash chromatography [0-100% EtOH:CH₂Cl₂:NH₄OH (50:8:1) in CH₂Cl₂] afforded the product as a white solid (427 mg, 96%). ¹H NMR (400 MHz, CDCl₃): 7.76 (d, J=2.0 Hz, 1H), 7.73 (d, J=8.8 Hz, 1H), 7.55-7.49 (m, 2H), 7.48-7.43 (m, 1H), 7.26 (dd, J=8.8, 2.1 Hz, 1H), 7.20-7.15 (m 1H), 5.23 (s, 2H), 4.77-4.68 (m, 1H), 3.45-3.37 (m, 2H), 3.03-2.94 (m, 2H), 2.71-2.59 (m, 2H), 1.80-1.72 (m, 2H). LRMS (APCI+) m/z 416.8 [M+H]⁺

8: 1-{[5-Chloro-1-(1-methanesulfonylpiperidin-4-yl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one

Methanesulfonyl chloride (23.0 μL, 0.297 mmol) was added to a cooled (0° C.) solution of compound 7 (62 mg, 0.149 mmol) and triethylamine (42.5 μL, 0.305 mmol) in anhydrous CH₂Cl₂ (2.5 mL) under N₂ and stirred at rt for 17 h. The reaction was diluted with CH₂Cl₂ (20 mL), washed successively with saturated aqueous NH₄Cl soln, water and brine (10 mL each), dried (MgSO₄) and the solvent removed under reduced pressure. Purification by flash chromatography (30-100% EtOAc in heptane) afforded a white solid (32 mg, 43%). ¹H NMR (400 MHz, CDCl₃): 7.77 (d, J=2.0, 1H), 7.56-7.44 (m, 4H), 7.26 (dd, J=8.7, 2.0 Hz, 1H), 7.19 (t, J=7.6 Hz, 1H), 5.24 (s, 2H), 4.74-4.64 (m, 1H), 4.03-3.96 (m, 2H), 2.93-2.83 (m, 5H), 2.61-2.48 (m, 2H), 1.82-7.72 (m, 2H). LRMS (APCI+) m/z 494.7 [M+H]⁺

9: 1-({5-Chloro-1-[1-(ethanesulfonyl)piperidin-4-yl]-1H-1,3-benzodiazol-2-yl}methyl)-3,3-difluoro-2,3-dihydro-1H-indol-2-one

Prepared by an analogous procedure to that described for compound 8 from compound 7. ¹H NMR (400 MHz, CDCl₃): δ 7.79 (d, J=2.0 Hz, 1H), 7.58-7.46 (m, 4H), 7.29-7.26 (m, 1H), 7.23-7.18 (m, 1H), 5.26 (s, 2H), 4.77-4.67 (m, 1H), 4.07-4.00 (m, 2H), 3.10-2.98 (m, 4H), 2.61-2.48 (m, 2H), 1.81-1.73 (m, 2H), 1.44 (t, J=7.4 Hz, 3H). LRMS (APCI+) m/z 508.8 [M+H]⁺

10: 1-{[5-Chloro-1-(oxan-4-yl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one

Prepared by an analogous procedure to intermediate 5A from intermediate 1A and 5-chloro-2-(chloromethyl)-1-(oxan-4-yl)-1H-1,3-benzodiazole. ¹H NMR (400 MHz, CDCl₃): δ 7.77 (d, J=2.0 Hz, 1H), 7.55-7.48 (m, 3H), 7.47-7.41 (m, 1H), 7.27-7.22 (m, 1H), 7.17 (t, J=7.6, 1H), 5.25 (s, 2H), 4.80-4.70 (m, 1H), 4.11 (dd, J=11.7, 4.6 Hz, 2H), 3.59 (td, J=12.0, 1.9 Hz, 2H), 2.55-2.42 (m, 2H), 1.67-1.62 (m, 2H). LRMS (APCI+) m/z 418.0 [M+H]⁺

11: 1-{[5-Chloro-1-(oxan-4-yl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3,6-trifluoro-2,3-dihydro-1H-indol-2-one

Prepared by an analogous procedure to intermediate 5A from 1E and 5-chloro-2-(chloromethyl)-1-(oxan-4-yl)-1H-1,3-benzodiazole. ¹H NMR (400 MHz, CDCl₃): δ 7.79-7.78 (m, 1H), 7.55-7.48 (m, 2H), 7.37-7.33 (m, 1H), 7.27-7.24 (m, 1H), 6.87-6.80 (m, 1H), 5.22 (s, 2H), 4.78-4.68 (m, 1H), 4.12 (dd, J=11.9, 4.6 Hz, 2H), 3.59 (td, J=12.0, 1.9 Hz, 2H), 2.57-2.43 (m, 2H), 1.67-1.59 (m, 2H). LRMS (APCI+) m/z 435.8 [M+H]⁺

12: 1-{[5-Chloro-1-(oxan-4-yl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3,7-trifluoro-2,3-dihydro-1H-indol-2-one

Prepared by an analogous procedure to intermediate 5A from 1F and 5-chloro-2-(chloromethyl)-1-(oxan-4-yl)-1H-1,3-benzodiazole. ¹H NMR (400 MHz, CDCl₃): δ 7.68 (d, J=2.0 Hz, 1H), 7.50 (d, J=8.7 Hz, 1H), 7.43-7.39 (m, 1H), 7.23-7.13 (m, 3H), 5.31 (s, 2H), 4.65-4.56 (m, 1H), 4.19 (dd, J=11.9, 4.6 Hz, 2H), 3.60 (td, J=12.0, 1.9 Hz, 2H), 2.62-2.49 (m, 2H), 1.88-1.81 (m, 2H). LRMS (APCI+) m/z 435.8 [M+H]⁺

13: 1-{[5-(Aminomethyl)-1-(3-methylbutyl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one

A solution of intermediate 5B (107 mg, 0.215 mmol) in TFA (1 mL) and CH₂Cl₂ (1 mL) was stirred at rt for 7 h. The volatiles were removed under reduced pressure and the residue partitioned between saturated aqueous NaHCO₃ solution (10 mL) and CH₂Cl₂ (10 mL) and separated. The aqueous layer was extracted with CH₂Cl₂ (2×10 mL), then CH₂Cl₂:iPrOH (˜3:1, 3×20 mL), the combined organic extracts washed with brine (10 mL), dried (Na₂SO₄) and the solvent removed under reduced pressure. Purification by flash chromatography (0-15% MeOH in CH₂Cl₂ with 1% NH₄OH) afforded a white solid (71 mg, 83%). ¹H NMR (400 MHz, DMSO-d₆) δ 7.77-7.72 (m, 1H), 7.61-7.51 (m, 2H), 7.45 (d, J=8.3 Hz, 1H), 7.34-7.19 (m, 3H), 5.28 (s, 2H), 4.30-4.22 (m, 2H), 3.78 (s, 2H), 1.72-1.61 (m, 1H), 1.59-1.50 (m, 2H), 0.95 (d, J=6.6 Hz, 6H). LRMS (APCI+) m/z 398.9 [M+H]⁺

The following compounds were prepared by the general BOC deprotection procedure described for Example 13.

TABLE 4 Compounds prepared via BOC deprotection

¹H NMR δ Example Name R (400 MHz, DMSO-d₆) LRMS AP-CI+ 14 1-{[5-(Aminomethyl)-1-(3- 4-F 7.70-7.62 (m, 1H), 7.55-7.53 (m, 416.9 [M + H]⁺ methylbutyl)-1H-1,3- 1H), 7.46 (d, J = 8.3 Hz, 1H), benzodiazol-2-yl]methyl}- 7.23 (dd, J = 8.3, 1.6 Hz, 1H), 3,3,4-trifluoro-2,3-dihydro- 7.20-7.16 (m, 1H), 7.12 (t, J = 1H-indol-2-one 8.9 Hz, 1H), 5.29 (s, 2H), 4.35- 4.22 (m, 2H), 3.79 (s, 2H), 1.73- 1.51 (m, 3H), 0.98-0.93 (m, 6H). 15 1-{[5-(Aminomethyl)-1-(3- 4-Cl 7.60 (t, J = 8.1 Hz, 1H), 7.54- 433.0 [M + H]⁺ methylbutyl)-1H-1,3- 7.52 (m, 1H), 7.46 (d, J = 8.2 Hz, benzodiazol-2-yl]methyl}-4- 1H), 7.32-7.26 (m, 2H), 7.23 (dd, chloro-3,3-difluoro-2,3- J = 8.3, 1.6 Hz, 1H), 5.29 (s, dihydro-1H-indol-2-one 2H), 4.29-4.23 (m, 2H), 3.80 (s, 2H), 1.74-1.52 (m, 3H), 0.98- 0.93 (m, 6H). 16 1-{[5-(Aminomethyl)-1-(3- 5-F 7.84-7.79 (m, 1H), 7.54-7.52 (m, 417.1 [M + H]⁺ methylbutyl)-1H-1,3- 3H), 7.37-7.32 (m, 1H), 7.22 (dd, benzodiazol-2-yl]methyl}- J = 8.4, 1.6 Hz, 1H), 5.28 (s, 3,3,5-trifluoro-2,3-dihydro- 2H), 4.29-4.22 (m, 2H), 3.78 (s, 1H-indol-2-one 2H), 1.73-1.62 (m, 1H), 1.58- 1.50 (m, 2H), 0.98-0.92 (m, 6H)

Example 17: Efficacy In Vitro

Compounds were subjected to RSV fusion assays and plaque reduction assays according to the following protocols.

RSV Fusion Assay

HEK293T ((ECACC 12022001) cells were cultured in T75 culture flasks in Dulbecco's medium (DMEM) containing 10% Foetal Bovine serum (FBS), 50 units per mL Penicillin and 50 μg/mL Streptomycin and warmed to 37° C. prior to use. The cells were passaged by first washing briefly with 5 mL Phosphate buffered saline (PBS), followed by addition of 2 mL of Trypsin Ethylenediaminetetraacetic acid (EDTA) to detach the cells. Once cells had detached from the flask, 8 mL media was then added to and the cells dispersed via pipetting against the bottom of the flask.

The cells were counted and diluted to 3×10⁵ cells/mL in fresh media. Two T75 flasks were each seeded with 15.6 mL diluted cells, cells were also subcultured at a ratio of between 1:2 and 1:10, to continue the stock. The flasks were then incubated for 24 h at 37° C. and 5% CO₂.

The plasmid DNA (for pFR-Luc and pcDNA3.1_Gal4/NFKB) to be transfected into the HEK 293T cells was first prepared in serum free media (Opti-MEM, Invitrogen), containing the transfection reagent FuGENE® 6 (Promega). Serum free media was placed in a 1.5 mL eppendorf tube then the FuGENE 6 was added into the media. The tube was vortexed for 1 s before being incubated at RT for 5 min. 7.79 ng of both pFR_luc and pCDNA3.1_A2_F plasmid DNA were added to tube 1 and 7.79 ng of pCDNA3.1_GAL4-NF-κB plasmid to tube 2. The tubes were vortexed for 1 second and then incubated at room temperature for 15 min. Each transfection mixture was then added into the media of one of the T75 flasks of 293T cells. Cells were cultured for 24 h at 37° C., 5% CO₂ in a humidified incubator.

Compounds were diluted (in a polypropylene round-bottomed 96 well plate) 1:3 in a twelve point dilution curve to give top [final] of either 25 μM, 3 μM, 1 μM or 500 nM. A control compound was included in every assay at a top concentration of 3 μM. Transfected cells were counted and diluted to 4×10⁵ cells/mL in fresh media. 50 μL of transfection population 1 were added to all wells of the 96 well flat bottom white opaque assay plates. 100 μL diluted compound (2 rows per compound), control compound (one row) and controls (DMSO (0% inhibition, four wells), 3 μM positive control (100% inhibition, four wells) and media (transfection population 1 only, four wells) were added to the appropriate wells. 50 μL of the diluted (4×10⁵ cells/mL) population 2 cells when then added to all wells, except the four wells of transfection population 1 only where an extra 50 μL of this cells population was added.

The plates were then incubated for 24 h at 37° C. and 5% CO₂. After this time, 100 μL was removed from all wells and 60 μL of ONE-Glo™ (Promega) reagent, pre-equilibrated to room temperature, was added. Plates were then incubated for 3 min at room temperature before luminescence was read, using the ONE-Glo protocol, on the GloMax Explorer System (Promega) multimode reader. Analysis was carried out in Dotmatics software. All raw data were background subtracted (subtraction of mean 3 μM positive control value), before IC₅₀ calculation.

Plaque Reduction Assay:

The plaque reduction assay was typically performed as follows. HEp-2 cells (ATCC, CCL23) were passaged in flasks and seeded in 96-well plates in DMEM containing antibiotics and supplemented with 10% FBS. During inoculation and subsequent incubation, cells were cultured in DMEM containing 3% FBS. 100 plaque forming unit (PFU)/well of RSV (RSV A2 VR-1540) was mixed with ten serial dilutions of compound. Subsequently, 100 μL of the virus/compound mixtures was added to confluent HEp-2 cell monolayers. The cells and virus/compound mixtures were incubated at 35° C. in a humidified 5% CO₂ incubator for 1 day.

Cells were washed twice with PBS before adding 50% v % v EtOH/MeOH, and then stored at −20° C. On the day of the staining, fixative was first removed from the plates. Plates were washed 3× with PBS. A pre-titrated amount of the primary antibody was added in 60 μL PBS/2% milk powder, and plates incubated for 1 h at rt. The plates were washed 3× with PBS/0.05% Tween20 before addition of goat anti-mouse horse radish peroxidase in 60 μL PBS/2% milk powder, and incubated for 1 h at rt. Following three wash steps with PBS/0.05% Tween20, 60 μL ready-to-use TrueBlue was added and plates were incubated at it for 10-15 min before adding MilliQ water. Plates were washed once with water, incubated for 30-60 min and after removal of water, air-dried in the dark.

Plates were scanned and analyzed using the Immunospot S6 UV analyzer, which is equipped with BioSpot analysis software for counting immunostained plaques (virospots). Plaque counts were used to calculate % infection relative to the mean of the spot count (SC) in the virus control wells for RSV. IC₅₀/IC₉₀ values were calculated as 50% or 90% reduction in signal, respectively, by interpolation of inhibition curves fitted with a 4-parameter nonlinear regression with a variable slope in GraphPad 5.0 (Prism). Alternatively, where noted the plaque reduction assay was performed as follows. Hep G2 cells (ECACC, 85011430) were passaged in flasks and seeded in 12-well plates in DMEM containing antibiotics and supplemented with 10% FBS, 24 h prior to inoculation. During inoculation and subsequent incubation, cells were cultured in DMEM containing 2% FBS. 75 plaque forming unit (PFU)/well of RSV (RSV A2, 0709161v) was mixed with 8 serial dilutions of compound. Subsequently, 200 μL of the virus/compound mixtures was added to confluent Hep G2 cell monolayers, for a 2 h infection, with manual shaking every 15 min. Infectious supernatant was then removed and replaced with 2 mL of overlay, comprising 4 parts of DMEM+2% FBS and 1 part 4% CMC, with 0.25% DMSO. The cells were incubated at 37° C. in a humidified 5% CO₂ incubator for 5 days.

Overlay was removed, and cells were washed with PBS before fixing with a mixture of 75% acetone 25% methanol for 3 minutes and replacing with fresh PBS. If staining did not start immediately plates were stored in PBS with 0.05% Tween20 (PBS-T) at 4° C. Staining was carried out whilst shaking at 37° C. First the plates were blocked with 500 uL PBS-T/2% milk powder per well, for 1 hr. This was then replaced with 250 uL PBS-T/2% milk powder containing a pre-titrated amount of the primary antibody (ab1128), for 90 min. The plates were washed 3×5 min with PBS-T, before addition of rabbit anti-goat horse radish peroxidase (AP106P) in 250 μL PBS-T/2% milk powder, and incubated for 1 hr. Following three wash steps with PBS-T, 250 μL of TrueBlue was added and plates were incubated at 10 min, before washing with tap water. Plates were then air-dried and stored in the dark.

Plates were scanned and analysed using the Immunospot S6 Macro analyzer, which is equipped with BioSpot analysis software for counting immunostained plaques. Plaque counts were input into dotmatics, where they were used to calculate % infection relative to the mean of the spot count in DMSO control wells. IC₅₀ values were calculated from the curve fit, as 50% reduction in signal, with minimum value of 0% and maximum 100%.

TABLE 5 Results RSV Fusion Assay RSV Plaque Reduction (n ≥ 2) Assay Strain A2 Compound IC₅₀ (nM)* IC₅₀ (nM) IC₉₀ (nM) 2 16 5.0 ^(†) 35 5 3.9 1.4 ^(†) 4.4 8 1.7 3.5 ^(‡) N.D. 9 2.2 12.6 ^(‡)  N.D. 10 17 6.4 ^(†) 53 13 2.6 4.1 ^(‡) N.D. *The given IC₅₀ represents the mean average of at least 2 independent experiments. ^(†) The given value is the IC₅₀ obtained in the plaque reduction assay performed as described and n = 1. ^(‡) The given IC₅₀ represents the mean average of at least 2 independent experiments obtained in the plaque reduction assay. Performed via the alternative conditions described above. ^(§) N.D. = not determined

Example 18: In Vitro Pharmacokinetics

Compounds were subjected to the following assays to investigate liver microsomal stability and permeability.

Microsomal incubation: Experimental Procedure

Pooled liver microsomes are purchased from a reputable commercial supplier and stored at −80° C. prior to use. Microsomes (final protein concentration 0.5 mg/mL), 0.1 M phosphate buffer pH 7.4 and test compound (final substrate concentration 3 μM, final DMSO concentration 0.25%) are pre-incubated at 37° C. prior to the addition of NADPH (final concentration 1 mM) to initiate the reaction. The final incubation volume is 50 uL. A control incubation is included for each compound tested where 0.1 M phosphate buffer pH 7.4 is added instead of NADPH (minus NADPH). Two control compounds are included with each species. All incubations are performed singularly for each test compound.

Each compound is incubated for 0, 5, 15, 30 and 45 min. The control (minus NADPH) is incubated for 45 min only. The reactions are stopped by transferring 20 μL of incubate to 60 μL MeOH at the appropriate time points. The termination plates are centrifuged at 2,500 rpm for 20 min at 4° C. to precipitate the protein.

Following protein precipitation, the sample supernatants are combined in cassettes of up to 4 compounds, internal standard is added and samples analysed by LC-MS/MS. From a plot of In peak area ratio (compound peak area/internal standard peak area) against time, the gradient of the line is determined. Subsequently, half-life and intrinsic clearance are calculated.

MDR1-MDCK Permeability: Experimental Procedure

MDR1-MDCK cells obtained from the NIH (Rockville, Md., USA) are used between passage numbers 6-30. Cells are seeded onto Millipore Multiscreen Transwell plates at 3.4×10⁵ cells/cm². The cells are cultured in DMEM and media is changed on day 3. On day 4 the permeability study is performed. Cell culture and assay incubations are carried out at 37° C. in an atmosphere of 5% CO₂ with a relative humidity of 95%. On the day of the assay, the monolayers are prepared by rinsing both basolateral and apical surfaces twice with Hanks Balanced Salt Solution (HBSS) at the desired pH warmed to 37° C. Cells are then incubated with HBSS at the desired pH in both apical and basolateral compartments for 40 min to stabilise physiological parameters.

The dosing solutions are prepared by diluting test compound with assay buffer to give a final test compound concentration of 10 μM (final DMSO concentration of 1% v/v). The fluorescent integrity marker lucifer yellow is also included in the dosing solution. Analytical standards are prepared from test compound DMSO dilutions and transferred to buffer, maintaining a 1% v DMSO concentration.

For assessment of A-B permeability, HBSS is removed from the apical compartment and replaced with test compound dosing solution. The apical compartment insert is then placed into a companion plate containing fresh buffer (containing 1% v/v DMSO). For assessment of B-A permeability, FIBSS is removed from the companion plate and replaced with test compound dosing solution. Fresh buffer (containing 1% v/v DMSO) is added to the apical compartment insert, which is then placed into the companion plate. At 60 min the apical compartment inserts and the companion plates are separated and apical and basolateral samples diluted for analysis. Test compound permeability is assessed in duplicate. Compounds of known permeability characteristics are run as controls on each assay plate.

Test and control compounds are quantified by LC-MS/MS cassette analysis using an 8-point calibration with appropriate dilution of the samples. The starting concentration (C₀) is determined from the dosing solution and the experimental recovery calculated from C₀ and both apical and basolateral compartment concentrations. The integrity of the monolayer throughout the experiment is checked by monitoring lucifer yellow permeation using fluorimetric analysis. Lucifer yellow permeation is high if monolayers have been damaged.

TABLE 6 Results Pharmacokinetic property Value Liver Microsomal Stability Compound 13: 16.9/9250/366 [t_(1/2) (min); rat/dog/human] Compound 9: 22.6/118/89.8 Compound 5: 21.3/63.3/3280 Compound 10: 18.2/12.4 /67.5 Permeability MDR1-MDCK Compound 13: 0.84/57.1 P_(app) (10⁻⁶ cms⁻¹) A-B/B-A Compound 9: 10.4/18.3 Compound 5: 0.21/14.5 Compound 10: 19.8/34.4

Example 19: Aqueous Formulation

The compound of Example 1 is formulated as a solution in 30% w/v captisol (i.e. sulfobutylether-beta-cyclodextrin) at pH4 according to the following procedure.

A carrier of 30% w/v captisol (i.e. sulfobutylether-beta-cyclodextrin) is prepared by weighing the required amount of captisol into a suitable vessel, adding approximately 80% of the final volume of water and magnetically stirring until a solution is formed. The carrier is then made up to volume with water.

An aqueous solution of a compound of Example 1 is prepared by weighing 175 mg of the compound into a suitable vessel and adding approximately 80% of the required volume of the carrier. Using an aqueous solution of hydrochloric acid, the pH is adjusted to pH2 and the resulting mixture is magnetically stirred until a solution is formed. The formulation is then made up to volume with carrier and the pH is adjusted to pH4 using an aqueous solution of sodium hydroxide.

Example 20 Tablet Composition

Tablets, each weighing 0.15 g and containing 25 mg of a compound of the invention are manufactured as follows:

Composition for 10,000 Tablets

Compound of the invention (250 g)

Lactose (800 g)

Corn starch (415 g)

Talc powder (30 g)

Magnesium stearate (5 g)

The compound of the invention, lactose and half of the corn starch are mixed. The mixture is then forced through a sieve 0.5 mm mesh size. Corn starch (10 g) is suspended in warm water (90 mL). The resulting paste is used to granulate the powder. The granulate is dried and broken up into small fragments on a sieve of 1.4 mm mesh size. The remaining quantity of starch, talc and magnesium is added, carefully mixed and processed into tablets.

Example 21: Injectable Formulation

Compound of the invention 200 mg Hydrochloric Acid Solution 0.1M or 4.0 to 7.0 Sodium Hydroxide Solution 0.1M q.s. to pH Sterile water q.s. to 10 mL

The compound of the invention is dissolved in most of the water (35° C.-40° C.) and the pH adjusted to between 4.0 and 7.0 with the hydrochloric acid or the sodium hydroxide as appropriate. The batch is then made up to volume with water and filtered through a sterile micropore filter into a sterile 10 mL amber glass vial (type 1) and sealed with sterile closures and overseals.

Example 22 Intramuscular Injection

Compound of the invention 200 mg Benzyl Alcohol 0.10 g Glycofurol 75 1.45 g Water for injection q.s to 3.00 mL

The compound of the invention is dissolved in the glycofurol. The benzyl alcohol is then added and dissolved, and water added to 3 mL. The mixture is then filtered through a sterile micropore filter and sealed in sterile 3 mL glass vials (type 1).

Example 23 Syrup Formulation

Compound of invention 250 mg Sorbitol Solution 1.50 g Glycerol 2.00 g Sodium benzoate 0.005 g Flavour 0.0125 mL Purified Water q.s. to 5.00 mL

The compound of the invention is dissolved in a mixture of the glycerol and most of the purified water. An aqueous solution of the sodium benzoate is then added to the solution, followed by addition of the sorbital solution and finally the flavour. The volume is made up with purified water and mixed well. 

The invention claimed is:
 1. A compound which is a benzimidazole of formula (I):

wherein: R¹ is —(CH₂)_(m)—R⁷,

R² is H, halo, —(CH₂)_(m)—NH₂, —(CH₂)_(n)—C(═NH)—NH₂ or —(CH₂)_(n)—NH—(CH₂)_(m)—NHR⁹; R³ is H, F or Cl; each of R⁴, R⁵ and R⁶ is independently H or F; R⁷ is C₁-C₆ alkyl, CF₃, —SO₂R¹¹, —NH—(CH₂)₂—(NH)_(r)—R⁸, —NH—CH(R⁸R⁹) or a group of formula (A):

W is —(CH₂)_(m)—, —CH₂—O—CH₂—, —CH₂—S—CH₂—, —(CH₂)_(r)—S(O)₂—CH₂— or (CH₂)_(r)—NR⁸—CH₂—; m is an integer of 1 to 3; n is 1 or 2; p is 1 and V is CH; or p is 0 and V is N; q is 0 or 1; r is 0 or 1; R⁸ is H, —SO₂R¹¹, —SO₂CF₃, —COR¹¹, —C(O)OR¹¹, —CON(R⁹)₂ or —(CH₂)_(n)SO₂R¹¹; R⁹ is H or C₁-C₆ alkyl, each R⁹ being the same or different when two are present; R¹⁰ is —SO₂R¹¹, —SO₂CF₃, —COR¹¹, —CON(R⁹)₂ or —(CH₂)_(n)SO₂R¹¹; and R¹¹ is C₁-C₆ alkyl; or a pharmaceutically acceptable salt thereof.
 2. The compound according to claim 1 wherein R¹ is —(CH₂)_(m)—R⁷ in which m is 2 or 3 and R⁷ is selected from: (i) —NH—(CH₂)₂—(NH)_(r)—R⁸ wherein r is 0 or 1 and R⁸ is selected from —SO₂Me, —SO₂Et and —SO₂CF₃; (ii) C₁-C₆ alkyl, CF₃ or —SO₂R¹¹; (iii) —NH—CH(R⁸R⁹) wherein R⁸ is —CONH₂ or —CONMe₂ and R⁹ is C₁-C₆ alkyl; (iv) a group of formula (A) in which p is 1, q is 0, V is CH and W is —(CH₂)_(r)—S(O)₂—CH₂— or —(CH₂)_(r)—NR⁸—CH₂— in which r is 0 and R⁸ is —SO₂Me or —SO₂Et; (v) a group of formula (A) in which p is 0, V is N, W is —(CH₂)_(m)— in which m is an integer of 1 to 3, q is 1 and R¹⁰ is —SO₂Me, —SO₂Et, —CONH₂ or —CONMe₂; and (vi) a group of formula (A) in which p is 0, V is N, q is 0 and W is —CH₂—CH₂—, —CH₂—S—CH₂—, —(CH₂)_(r)—S(O)₂—CH₂— or —(CH₂)_(r)—NR⁸—CH₂— in which r is 0 or 1 and R⁸ is —SO₂Me, —SO₂Et or —COMe.
 3. The compound according to claim 1 wherein: R¹ is

in which R⁸ is H, —SO₂R¹¹, —COMe, —C(O)OR¹¹, —CON(R⁹)₂ or —(CH₂)_(n)SO₂R¹¹.
 4. The compound according to claim 3 wherein: —SO₂R¹¹ is —SO₂Me or —SO₂Et; —CON(R⁹)₂ is —CONH₂ or —CONMe₂; and —(CH₂)_(n)SO₂R¹¹ is —CH₂CH₂SO₂Me.
 5. The compound according to claim 1 wherein R² is Cl or —CH₂NH₂.
 6. The compound according to claim 1 wherein the group of formula (A) is selected from the following structures:


7. The compound according to claim 1 which is selected from: 1-{[5-Chloro-1-(4,4,4-trifluorobutyl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one; 1-({5-Chloro-1-[3-(4-methanesulfonylpiperazin-1-yl)propyl]-1H-1,3-benzodiazol-2-yl}methyl)-3,3-difluoro-2,3-dihydro-1H-indol-2-one; 1-[(5-Chloro-1-{3-[(2-methanesulfonylethyl)amino]propyl}-1H-1,3-benzodiazol-2-yl)methyl]-3,3-difluoro-2,3-dihydro-1H-indol-2-one; 1-({5-Chloro-1-[3-(3-methanesulfonylpyrrolidin-1-yl)propyl]-1H-1,3-benzodiazol-2-yl}methyl)-3, 3-difluoro-2,3-dihydro-1H-indol-2-one; 1-{[5-Chloro-1-(3-methanesulfonylpropyl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one; tert-Butyl 4-{5-chloro-2-[(3,3-difluoro-2-oxo-2,3-dihydro-1H-indol-1-yl)methyl]-1H-1,3-benzodiazol-1-yl}piperidine-1-carboxylate; 1-{[5-Chloro-1-(piperidin-4-yl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one; 1-{[5-Chloro-1-(1-methanesulfonylpiperidin-4-yl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one; 1-({5-Chloro-1-[1-(ethanesulfonyl)piperidin-4-yl]-1H-1,3-benzodiazol-2-yl}methyl)-3,3-difluoro-2,3-dihydro-1H-indol-2-one; 1-{[5-Chloro-1-(oxan-4-yl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one; 1-{[5-Chloro-1-(oxan-4-yl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3,6-trifluoro-2,3-dihydro-1H-indol-2-one; 1-{[5-Chloro-1-(oxan-4-yl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3,7-trifluoro-2,3-dihydro-1H-indol-2-one; 1-{[5-(Aminomethyl)-1-(3-methylbutyl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3-difluoro-2,3-dihydro-1H-indol-2-one; 1-{[5-(Aminomethyl)-1-(3-methylbutyl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3,4-trifluoro-2,3-dihydro-1H-indol-2-one; 1-{[5-(Aminomethyl)-1-(3-methylbutyl)-1H-1,3-benzodiazol-2-yl]methyl}-4-chloro-3,3-difluoro-2,3-dihydro-1H-indol-2-one; and 1-{[5-(Aminomethyl)-1-(3-methylbutyl)-1H-1,3-benzodiazol-2-yl]methyl}-3,3,5-trifluoro-2,3-dihydro-1H-indol-2-one; and the pharmaceutically acceptable salts thereof.
 8. A pharmaceutical composition which comprises a compound as defined in claim 1 and a pharmaceutically acceptable carrier or diluent.
 9. A method of treating a subject suffering from or susceptible to an RSV infection, which method comprises administering to said subject an effective amount of a compound as defined in claim
 1. 10. A pharmaceutical composition which comprises (a) a compound as defined in claim 1, and (b) one or more further therapeutic agents, together with a pharmaceutically acceptable carrier or diluent, wherein the one or more further therapeutic agents is selected from the group consisting of: (i) a RSV nucleocapsid(N)-protein inhibitor; (ii) a protein inhibitor, such as one that inhibits the phosphoprotein (P) protein and/or large (L) protein; (iii) an anti-RSV monoclonal antibody, such as an F-protein antibody; (iv) an immunomodulating toll-like receptor compound; (v) a respiratory virus anti-viral, such as an anti-influenza and/or anti-rhinovirus compound; and (vi) an anti-inflammatory compound.
 11. A process for producing a pharmaceutically acceptable salt as defined in claim 1, which process comprises treating a benzimidazole of formula (I) as defined in claim 1 with a suitable acid in a suitable solvent.
 12. The process according to claim 11, wherein the acid is selected from hydrochloric acid, hydrobromic acid, hydroiodic acid, sulphuric acid, nitric acid, phosphoric acid, methanesulfonic acid, benzenesulphonic acid, formic acid, acetic acid, trifluoroacetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, fumaric acid, maleic acid, lactic acid, malic acid, tartaric acid, citric acid, ethanesulfonic acid, aspartic acid and glutamic acid.
 13. The method according to claim 9, which method further comprises administering to the subject a further therapeutic agent selected from the group consisting of: (i) a RSV nucleocapsid(N)-protein inhibitor; (ii) another protein inhibitor, such as one that inhibits the phosphoprotein (P) protein and/or large (L) protein; (iii) an anti-RSV monoclonal antibody, such as an F-protein antibody; (iv) an immunomodulating toll-like receptor compound; (v) another respiratory virus anti-viral, such as an anti-influenza and/or anti-rhinovirus compound; and (vi) an anti-inflammatory compound. 